drm: atmel-hlcdc: add the missing DRM_ATOMIC flag

The atmel-hlcdc driver already supports atomic operations, add the
missing DRM_ATOMIC flag to expose the atomic features to userspace.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>

drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c

@@ -486,7 +486,8 @@ static const struct file_operations fops = {
 
 static struct drm_driver atmel_hlcdc_dc_driver = {
 	.driver_features = DRIVER_HAVE_IRQ | DRIVER_GEM |
-			   DRIVER_MODESET | DRIVER_PRIME,
+			   DRIVER_MODESET | DRIVER_PRIME |
+			   DRIVER_ATOMIC,
 	.preclose = atmel_hlcdc_dc_preclose,
 	.lastclose = atmel_hlcdc_dc_lastclose,
 	.irq_handler = atmel_hlcdc_dc_irq_handler,